Final Update: I ran matching loads in CCI SPP and CCI SPPM. The SPPM are harder. My testing puts this to bed for me and conclusively proves that harder SPPM, SRP and SRPM can cause breech cutting around the primer cup using weak loads because the primer does not deform to seal the primer pocket. Picture of SPPM vs. SPP:https://lh3.googleusercontent.com/-E...Large%2529.jpg
These two cases are representative of loads fired. I've since traded all my SPPM for SPP. The SPP indent and primer flow is more pronounced, and it's much more noticeable in real life. __________________________________________________________________________

Update 2/19/12: I ran the 4.9gr Unique load and primer flow and indent depth appears identical to the 4.7gr load. So, >4.7gr provides enough pressure for primer flow that should seal the pocket. Also, I just swapped 4k SPPM with SPP at the local gun show. The guy will trade my remaining 5k SPPM next show. So, that will be the end of it. If I'd have known SPPM and low pressure loads was the cause sooner I'd had swapped them already.
__________________________________________________________________________

- ORIGINAL POST -

I have a Gen3 Glock 17 and a former Gen2 Glock 19 I've run lots of (old red box CCI) SPPM though. My current Gen3 Glock 17 has about 7-8k through it (maybe more) and the Gen2 Glock 19 had >20k. About 2/3 of these have been these SPPM because I bought about 30k in FTF deals for $10-$20k back in the crazy price days. And, I've run a few hundred SRP and SRPM as well. Loads have cycled fine with no change in accuracy. And, I do not change my powder charge. I've always known all these 124gr FMJ/Plated SPPM loads are well under-pressure as the bulk have run only 1000-1050fps, or even less for some LRN loads used in the Glock 19 w/ LWD and KKM barrels.

Breech face gas cutting has occured (consistent with the primer cup), and has for some time in this Glock 17, and it was the same in the G19. I've also run these loads in other guns with similar results (e.g. slight breech face marks), though the ring has not formed due to lower volume shooting. I've even run them in once-fired, sorted .45acp brass (with a hammer-fired 1911: Unique 3.9-4.0gr w/ 200gr LSWC @ 1.135", which is a tame load) to rule out over-pressure, flash hole difference/size, primer impact deformation, stretched primer pocker (e.g. brass issues), etc. (same result). It does not seem to matter if I use a faster or slower powder, with mixed brass or not, nor does it seem to matter using once-fired brass or more-fired. I have not observed damage to primers, fired primers remain seated (i.e. are not loose), and new primers seat fine in fired brass (i.e. smooth, with slight resistance and seat fully) using two different Dillon SD progressives.https://lh4.googleusercontent.com/-8...Cutting003.jpghttps://lh3.googleusercontent.com/-9...Cutting006.jpg

So, becoming more curious only recently, I've narrowed my theory of late, and do not think brass is the culprit. I believe the harder primer cup is not expanding to allow a tight primer pocket seal at the lower handgun pressures, 9mm or .45acp. Meaning, not over-pressure or a streched primer pocket, but under-pressure (weak) loads with these harder older red box CCI SPPM primers. I do think higher 9mm pressure (vs. .45acp) exacerbates it, but the 9mm pressure, at least the weak 1000-1050fps loads I've run, is still below the pressures needed to seal these SPPM in the primer pocket, meaning more gas escapes. And, since most of the cutting in my 9mm is from (older red box CCI) SPPM, the hardness of the cup must be more like rifle primers. I've heard/read, and have experienced myself via light primer strikes, that these CCI SPPM are harder than current production and much more like rifle primers. So, none of this may matter if you don't have those, but could be applicable if you plan to run SRP/SRPM (i.e. harder cup primers) in 9mm.

If I push the 9mm faster, to +p or +p+, it may go away or lessen, and I'm testing that now running all loads at ~1150fps. I have already noticed differences in primer flow patterns (see image below). But, I can't push .45acp fast enough if low pressure is the cause.

I've pretty much always run weak to mid-level loads. All along, and for many years, I thought the issue was using mixed brass and I did not want to sort. That, and I did not really care since I knew the loads were safe. But, I'm beginning to think conclusively that too weak loads using harder primers is the issue. More rounds downrange with hotter loads will prove or disprove that theory.

I view Glocks as tools, and I consider Glocks "throwaway" guns somewhat anyway. I consider this cosmentic for now, and will monitor to see if breech integrity could become compromised if ring gets deeper. Obviously, this does not matter to me in this Glock 17 (and did not matter in my former Glock 19) as I keep running SPPM, even SRP and SRPM. But, I don't use SPPM, SRP or SRPM in any volume in my other 9mms due to this, nor would I run them in any 9mm I really cared about, and stick with using SPP instead for now. Even if the issue goes away, it may be just these older red box CCI primers, but I won't know that for sure as I've not run other SPPM in high volume. Regardless, I often share SPPM, even SRP and SRPM run fine in 9mm. And, they do. I figured I'd share this as a PSA to let folks know your breech may show accelated wear using SPPM, SRP or SRPM if you run weak loads. To me, though I'll bump up the load to see if it goes away, it's worth it given what I paid for these primers and how cheap Glocks are since I've saved more than enough to buy the gun again.

Zombie Steve

02-05-2012 22:34

Gas coming around the primer is usually a pretty major sign of overpressure. Might help if you shared your load data with us.

I'm a little saucy after the super bowl fiesta, so I'll re-read this in the morning.

:faint:

Colorado4Wheel

02-05-2012 22:44

The Rifle primers may not be sealing well due to lack of pressure and then gas leaks past and causes the cutting.

fredj338

02-05-2012 23:20

It takes very little tolerance gap to get gas blowback. Why brass w/ enlarged pockets should be tossed. Your theory about smaller flash holes is interesting, but I am betting improper primer fit + high pressures.

cole

02-06-2012 00:04

Quote:

Originally Posted by Zombie Steve
(Post 18536678)

Gas coming around the primer is usually a pretty major sign of overpressure. Might help if you shared your load data with us. I'm a little saucy after the super bowl fiesta, so I'll re-read this in the morning. :faint:

I've run Unique, 700x, BE, Solo 1000 and TG (and maybe some others?) from <1000fps to (a handful at)1200+ FPS with 115gr and 124gr FMJ, 147gr (~900-950fps) and 125gr LRN (<1000fps), and 125gr plated. I've had brass barely dribble out of the gun to those that fly out with purpose. Has not mattered (but I can say more loads have been weaker). No signs of overpressure, brass has seen 1-2 reloads and load data is well within specs given bullet, charge and OAL. I've run too many loads to list them. We're talking >40k rounds over many years (mixed SPP (lots), SPPM (lots), SRP (few) and SRPM(few)) in a variety of 9mms, but mainly Glocks in high volume shooting. I've had this ring, or marks on the breech, to varying degrees in all my high volume 9mm guns that have run lots of SPPM. Again, I never sort brass by times fired or headstamp, but I have >30k in 9mm brass so brass does not see tons of reloads anyway. Maybe I just suck reloading, and always have then it would seem, but my money is on the use of SPPM, SPR and SRPM, and those that have run high volume, mixed headstamp 9mm with SPPM, SRP or SRPM can make the best comparison. I've recently been shooting hotter loads (~1150-1200fps w/ 124-125gr vs. 1000-1100fps) so we'll see if that changes anything, though it may take a few thousand rounds to tell.

Quote:

Originally Posted by Colorado4Wheel
(Post 18536709)

The Rifle primers may not be sealing well due to lack of pressure and then gas leaks past and causes the cutting.

Most of the cutting has been with SPPM. I've got >20k with those and less than 1k with rifle primers in 9mm. I agree with the pressure seal as the clear cause. I've run 9mm loads weak and (a few) hot. Does not seem to matter, but most loads have been weak-mid. I don't run real weak loads any more. I think the harder cup of the SPPM, SRP and SRPM has something to do with it indeed. And, not sorting brass by headstamp can't help. I can say it happens in the 9mm hammer-fired CZ and Beretta too, but I've not run those in high volume with SPPM like Glocks and the marks have been very slight and hardly noticeable. Regardless, it's only an issue using SPPM, SRP and SRPM.

Quote:

Originally Posted by fredj338
(Post 18536832)

It takes very little tolerance gap to get gas blowback. Why brass w/ enlarged pockets should be tossed. Your theory about smaller flash holes is interesting, but I am betting improper primer fit + high pressures.

Low pressure and high pressure loads (based on velocity and published load data) seem to get the same result using SPPM, SRP and SRPM, but I've not shot as many high pressure loads. I do not have a tool to measure CUP pressure so have to go by velocity, load data, felt recoil and appearance of primers. All are within norms. I agree it's a primer vs. primer pocket fit issue, and think the harder cup plays a part. The smaller flash hole theory is just conjecture on my part since SPPM .45acp loads have not (yet) had issues. With >30k of 9mm brass, and the way I cycle through it, most brass has only seen 1-2 reloads. It's all mixed headstamp though. I wonder if SB brass would solve it actually as those suckers are tight. Honestly, I've not worried too much about it, and it does not bother me much on my range/game beater Glocks, just thought I'd share with the class.

gasboffer

02-06-2012 09:23

I had the same thing with a Glock 19. Finally found the reason.....Remington SPP had pin-holes at the edge of the primer after firing. Threw the rest of the primers (about 600)in the garden. Solved the problem.

dla

02-06-2012 10:00

When I've had that it was due to the brass - not the primer. I had problems with Remington brass.

cole

02-13-2012 21:42

I've updated my post with some new information. And, a few edits to narrow focus in on the harder primer cup theory.

Colorado4Wheel

02-13-2012 22:16

So now you agree that the Rifle Primers are not sealing and that is causing the problem. Before you didn't. I'm confused. Editing your first post didn't help.

cole

02-13-2012 23:01

Quote:

Originally Posted by Colorado4Wheel
(Post 18575827)

So now you agree that the Rifle Primers are not sealing and that is causing the problem. Before you didn't. I'm confused. Editing your first post didn't help.

I'm likewise confused. I never disagreed that harder rifle primers could be a cause (i.e. play a part). Even your own reply stated rifle primer hardness "may" be the cause, not "is" the cause. What I believe now, with more data, and with greater certainty, is that the hardness of rifles primers is the cause (i.e. play the part). Meaning, for example, it's not the brass and not over-pressure. Basically, it's an under-pressure issue inherent in using harder rifle primers in 9mm and .45acp. Also important, at least to me, is that I also now think the older red box CCI SPPM, which are most of the SPPM I've used, are harder (because they are in my experience) and, aside from light primer strikes, can also behave more like rifle primers relative to expansion to gas seal the primer pocket. Is that not what's said above and in my replies?

I'm a curios fellow. Reloading is a hobby. This may not be news to you (even though your reply stated "may" not "is" in terms of certainty of cause), but, in terms less conjecture supported by actual data, it's news to me as far as certainty goes. I'm sharing as other reloaders may be interested given many condone (as I do) using SPPM, SRP and SRPM in 9mm. My main message is that it works, but you could get gas cutting on your breech regardless of load or brass used. Does not bother me on my high volume Glocks, and I never thought much of it before when getting gas cutting using SPPM in loads I knew were safe. But, it might matter to some, and would matter to me on some other guns I own.

Hope that helps clear things up. :thumbsup:

WiskyT

02-14-2012 16:55

Quote:

Originally Posted by Colorado4Wheel
(Post 18575827)

So now you agree that the Rifle Primers are not sealing and that is causing the problem. Before you didn't. I'm confused. Editing your first post didn't help.

I've been confused through this whole thread. WTF is the purpose of using the wrong primer and ruining the breach face?

ColoCG

02-14-2012 18:42

Quote:

Originally Posted by WiskyT
(Post 18579314)

I've been confused through this whole thread. WTF is the purpose of using the wrong primer and ruining the breach face?

:thumbsup: I whole heartedly agree with you. It doesn't seem worth it. Or make sense!

dkf

02-14-2012 20:01

Quote:

Originally Posted by WiskyT
(Post 18579314)

I've been confused through this whole thread. WTF is the purpose of using the wrong primer and ruining the breach face?

Apparently trying to save money. Don't see the point when you can get Wolf pistol primers for around $16 per 1k. Kinda seems pennywise and pound foolish to me but whatever.

justinsaneok

02-14-2012 20:10

Quote:

Originally Posted by dkf
(Post 18580293)

Apparently trying to save money. Don't see the point when you can get Wolf pistol primers for around $16 per 1k. Kinda seems pennywise and pound foolish to me but whatever.

Well how much are slides? If he has enough primers it might be worth it.:rofl:

cole

02-15-2012 10:49

Quote:

Originally Posted by WiskyT
(Post 18579314)

I've been confused through this whole thread. WTF is the purpose of using the wrong primer and ruining the breach face?

Quote:

Originally Posted by ColoCG
(Post 18579876)

:thumbsup: I whole heartedly agree with you. It doesn't seem worth it. Or make sense!

It's the SPPM that did most of the breech face cutting and I think now that these (red box CCI primers) have a cup hardness more like rifle primers. The SRP and SRPM use is very low volume by comparison and something I was just more curious about in 9mm. That's part of the hobby part in reloading. And, I just clarified that in my OP.

Many reloaders state SPPM (and also SRP and SRPM) run in 9mm. They do. What I've found conclusively, at least to myself, is that it's not the brass (e.g. stretched pocket) and not over-pressure, it's primer hardness and under-pressure. So, aside from being more prone to light primer strikes, hard primers may cut your breech face (but, maybe just with weaker loads?). That might be useful information to some reloaders. I'm sharing this to share my experience with other reloaders who may consider using SPPM (or SRP/SPRM), because, well, I think sharing information is something reloaders should do.

Also, there was a small primer shortage a while back you may have missed and reloaders were running what they could get. A cheap gun (like a Glock) you actually shoot often, over time, is much, much more expensive to feed than purchase.

Quote:

Originally Posted by dkf
(Post 18580293)

Apparently trying to save money. Don't see the point when you can get Wolf pistol primers for around $16 per 1k. Kinda seems pennywise and pound foolish to me but whatever.

Quote:

Originally Posted by justinsaneok
(Post 18580342)

Well how much are slides? If he has enough primers it might be worth it.:rofl:

How quickly some forget when primers were short and ran up to $40/k (or more). I was getting bulk SPPM for $10-$20/k in FTF deals. Run >10k a year in those days and do the math. I have, and already saved enough to buy this gun again. The math is different for low vs. high volume shooters. And, different if you ignore the past.

justinsaneok

02-15-2012 13:51

Quote:

Originally Posted by cole
(Post 18582950)

It's the SPPM that did most of the breech face cutting and I think now that these (red box CCI primers) have a cup hardness more like rifle primers. The SRP and SRPM use is very low volume by comparison and something I was just more curious about in 9mm. That's part of the hobby part in reloading. And, I just clarified that in my OP.

Many reloaders state SPPM (and also SRP and SRPM) run in 9mm. They do. What I've found conclusively, at least to myself, is that it's not the brass (e.g. stretched pocket) and not over-pressure, it's primer hardness and under-pressure. So, aside from being more prone to light primer strikes, hard primers may cut your breech face. That might be useful information to some reloaders. I'm sharing this to share my experience with other reloaders who may consider using SPPM (or SRP/SPRM), because, well, I think sharing information is something reloaders should do.

Also, there was a small primer shortage a while back you may have missed and reloaders were running what they could get. A cheap gun (like a Glock) you actually shoot often, over time, is much, much more expensive to feed than purchase.

How quickly some forget when primers were short and ran up to $40/k (or more). I was getting bulk SPPM for $10-$20/k in FTF deals. Run >10k a year in those days and do the math. I have, and already saved enough to buy this gun again. The math is different for low vs. high volume shooters. And, different if you ignore the past.

I remember how crazy it was, it will be again. I'm just now buying in bulk what a difference. Casting my own and bulk primers and powder = lotsa fun, lotsa practice.
Lot of guys I know use them in light loads oddly enough. Said it made them more consistent when on the edge of power factor or so I was told.

ColoCG

02-15-2012 14:35

[QUOTE=cole;18582950]It's the SPPM that did most of the breech face cutting and I think now that these (red box CCI primers) have a cup hardness more like rifle primers.

Also, there was a small primer shortage a while back you may have missed and reloaders were running what they could get. A cheap gun (like a Glock) you actually shoot often, over time, is much, much more expensive to feed than purchase.

I seem to have heard about that shortage, but since I had already gone through a primer shortage 15+ years before that, I was well prepared for the last one.

Actually years ago, all I bought was SPPM and used them in both .357mag., 9mm, and.38spl.to consolidate to one primer type, I never had any problems like you had, or I would have stopped the use immediatly.

It didn't take long to realize that spp were cheaper and the practice of using only one primer wasn't worth it.

WiskyT

02-15-2012 21:00

The use of small pistol magnum primers would not pit your breach face. I don't know what's going on with that gun/ammo, but it is not caused by using magnum pistol primers.

dkf

02-15-2012 21:18

Quote:

How quickly some forget when primers were short and ran up to $40/k (or more). I was getting bulk SPPM for $10-$20/k in FTF deals. Run >10k a year in those days and do the math. I have, and already saved enough to buy this gun again. The math is different for low vs. high volume shooters. And, different if you ignore the past.

Thats why when shooting 10k rounds per year its a good idea to stockpile primers and get them while they are cheap. Apparently you were one of the ones that forgot.

cole

02-16-2012 11:12

Quote:

Originally Posted by WiskyT
(Post 18585596)

The use of small pistol magnum primers would not pit your breach face. I don't know what's going on with that gun/ammo, but it is not caused by using magnum pistol primers.

Well, I can tell you the SPPM caused breech face pitting with >15k in a G19 and >5k in this G17 with mostly loads on the lower-mid end of data. Take my word for it or not. I thought it was an issue with mixed brass (I did not want to sort) and since I never cared before I never thought more of it. What I think the deal is in using SPPM is that loads were not being pushed fast enough. So, now I'm curious and I'm now pushing all FMJ loads to 1150+ fps to test that theory. Running lower volume hotter loads (e.g. to match defensive loads) and much higher volume weak-mid loads (e.g. to make min. PF) could have made it hard to tell, not that I was really giving much mind to the breech face pitting anyway since I knew the loads were safe.

Quote:

Originally Posted by dkf
(Post 18585690)

Thats why when shooting 10k rounds per year its a good idea to stockpile primers and get them while they are cheap. Apparently you were one of the ones that forgot.

You know, there are other calibers than 9mm. Pre-runup, I reloaded more .45acp, meaning I had lots of LPP. Cute comment though, and both amazingly helpful and incredibly constructive. Thanks. :thumbsup:

Quote:

Originally Posted by ColoCG
(Post 18583931)

I seem to have heard about that shortage, but since I had already gone through a primer shortage 15+ years before that, I was well prepared for the last one. ...

If 9mm used the same primer as .45acp I'd have been set. It didn't at the time, so I had enough LPP, but not SPP. But, I never though much of using SPPM (which I got cheap in those days) and I never cared about the breech face pitting thinking it was due to using mixed brass (I did not care to sort). Now, with more and more SPP .45acp showing up using the same primer is possible. Needless to say I'm set now regardless. And, I think bumping all loads could solve the problem anyway. We'll see. :wavey: